Origin And Its Geological Significance Of The Xiaoshuijing Granite Host Of Mo Mineralisation In The Tengchong Terrane, SW China

The western Yunnan region has become one of the frontier and hotspot research areas all over the world in recent years,due to its complicated process of orogenesis and evolution.Widespread in the Tengchong block of western Yunnan region are granites,with closely related to the formation and development of tungsten-tin,lead-zinc,and molybednum deposits in Tengchong area.Meanwhile,these granites are the“probe”and“window”to reveal the evolution of continental dynamics and geodynamics.The research method of this thesis was based on petrology,zircon U-Pb geochronology,U-Pb zircon age,and molybdenite Re-Os age of the Xiaoshuijing molybdenum mineralized granite in the Tengchong area of western Yunnan,and the detailed study of whole rock geochemical data and Hf isotope data,then combined with regional data analysis.The research results and new insights have been shown as following:1)The mineralogy and geochemistry of the Xiaoshuijing granite indicate that the granites in the Tengchong area of western Yunnan have high SiO₂?content>72%?,high Al content?12.86–15.15%?,alkaline,peraluminous?A/CNK=1.62-1.87,with an average of 1.75?,they are the alkaline series of peraluminous granites.2)The zircon saturation temperature(T_Zr)is 550-641?.The temperature of the Xiaoshui granite calculated using Ti-in-zircon thermometer is between 569⁷64?with an average of 675.9?,which roughly represents the crystallization of the temperature of the magma and also proves this is cryogenic granite.3)It is concluded that the Xiaoshuijing granite was formed in ancient continental crust in Paleoproterozoic according to the granite zircon Hf isotopic composition,?Hf?t?-t diagram,trace and rare earth element features.The Xiaoshuijing granite was produced in the transitional environment between India and Eurasian plate with collision and post-collision,it has undergone a thickening of the crust to melt by the continental collision and briefly and locally stretched after the collision peak period.4)Molybdenite from Xiaoshuijing granite has molybdenum mineralization,the age of Re-Os is 63.7±2.3Ma,the zircon U-Pb age is 64.60±0.41Ma from granite,that all indicate there is a closure time relationship between magmatic activity and mineralization.Therefore,the molybdenum mineralisation is closely related to the Early Paleogene magmatism.5)Xiaoshuijing molybdenum mineralization granite and mineralization belongs to the plate and collision-after a collision with peraluminous granite,is Land collides with land caused the crustal thickening and cause to melt,and is a short,local tension after collision peak stage.At the same time,the geological characteristics of Xiaoshuijing molybdenum mineralized granite in the whole tectonic evolution stage and tectonic environment also indicate that there may be new molybdenum metallogenic potential in this area.